Three-dimensional finite element simulation and reconstruction of jointed rock models using CT scanning and photogrammetry

The geometry of joints has a significant influence on the mechanical properties of rocks.To simplify the curved joint shapes in rocks,the joint shape is usually treated as straight lines or planes in most laboratory experiments and numerical simulations.In this study,the computerized tomography (CT) scanning and photogrammetry were employed to obtain the internal and surface joint structures of a limestone sample,respectively.To describe the joint geometry,the edge detection algorithms and a three-dimensional (3D) matrix mapping method were applied to reconstruct CT-based and photogrammetry-based jointed rock models.For comparison tests,the numerical uniaxial compression tests were conducted on an intact rock sample and a sample with a joint simplified to a plane using the parallel computing method.The results indicate that the mechanical characteristics and failure process of jointed rocks are significantly affected by the geometry of joints.The presence of joints reduces the uniaxial compressive strength (UCS),elastic modulus,and released acoustic emission (AE) energy of rocks by 37%–67%,21%–24%,and 52%–90%,respectively.Compared to the simplified joint sample,the proposed photogrammetry-based numerical model makes the most of the limited geometry information of joints.The UCS,accumulative released AE energy,and elastic modulus of the photogrammetry-based sample were found to be very close to those of the CT-based sample.The UCS value of the simplified joint sample (i.e.38.5 MPa) is much lower than that of the CT-based sample (i.e.72.3 MPa).Additionally,the accumulative released AE energy observed in the simplified joint sample is 3.899 times lower than that observed in the CT-based sample.CT scanning provides a reliable means to visualize the joints in rocks,which can be used to verify the reliability of photogrammetry techniques.The application of the photogrammetry-based sample enables detailed analysis for estimating the mechanical properties of jointed rocks.

Influence of pore structure heterogeneity on channeling channels during hot water flooding in heavy oil reservoir based on CT scanning

Hot water flooding is an effective way to develop heavy oil reservoirs.However,local channeling channels may form,possibly leading to a low thermal utilization efficiency and high water cut in the reservoir.The pore structure heterogeneity is an important factor in forming these channels.This study proposes a method that mixes quartz sand with different particle sizes to prepare weakly heterogeneous and strongly heterogeneous models through which hot water flooding experiments are conducted.During the experiments,computer tomography(CT)scanning identifies the pore structure and micro remaining oil saturation distribution to analyze the influence of the pore structure heterogeneity on the channeling channels.The oil saturation reduction and average pore size are divided into three levels to quantitatively describe the relationship between the channeling channel distribution and pore structure heterogeneity.The zone where oil saturation reduction exceeds 20%is defined as a channeling channel.The scanning area is divided into 180 equally sized zones based on the CT scanning images,and threedimensional(3D)distributions of the channeling channels are developed.Four micro remaining oil distribution patterns are proposed,and the morphology characteristics of micro remaining oil inside and outside the channeling channels are analyzed.The results show that hot water flooding is more balanced in the weakly heterogeneous model,and the oil saturation decreases by more than 20%in most zones without narrow channeling channels forming.In the strongly heterogeneous model,hot water flooding is unbalanced,and three narrow channeling channels of different lengths form.In the weakly heterogeneous model,the oil saturation reduction is greater in zones with larger pores.The distribution range of the average pore size is larger in the strongly heterogeneous model.The network remaining oil inside the channeling channels is less than outside the channeling channels,and the hot water converts the network remaining oil into cluster,film,and droplet remaining oil.

Fatigue properties and damage constitutive model of salt rock based on CT scanning

To investigate the macroscopic fatigue properties and the mesoscopic pore evolution characteristics of salt rock under cyclic loading,fatigue tests under different upper-limit stresses were carried out on salt rock,and the mesoscopic pore structures of salt rock before and after fatigue tests and under different cycle numbers were measured using CT scanning instrument.Based on the test results,the effects of the cycle number and the upper-limit stress on the evolution of cracks,pore morphology,pore number,pore volume,pore size,plane porosity,and volume porosity of salt rock were analyzed.The failure path of salt rock specimens under cyclic loading was analyzed using the distribution law of plane porosity.The damage variable of salt rock under cyclic loading was defined on basis of the variation of volume porosity with cycle number.In order to describe the fatigue deformation behavior of salt rock under cyclic loading,the nonlinear Burgers damage constitutive model was further established.The results show that the model established can better reflect the whole development process of fatigue deformation of salt rock under cyclic loading.

Analysis of the microstructure of microbial solidified sand and engineering residue based on CT scanning

A close relationship exists between the pore network structure of microbial solidified soil and its macroscopic mechanical properties.The microbial solidified engineering residue and sand were scanned by computed tomography(CT),and a three-dimensional model of the sample was established by digital image processing.A spatial pore network ball-stick model of the representative elementary volume(REV)was established,and the REV parameters of the sample were calculated.The pore radius,throat radius,pore coordination number,and throat length were normally distributed.The soil particle size was larger after solidification.The calcium carbonate content of the microbial solidified engineering residue’s consolidated layer decreased with the soil depth,the porosity increased,the pore and throat network developed,and the ultimate structure was relatively stable.The calcium carbonate content of the microbial solidified sand’s consolidated layer decreased and increased with the soil depth.The content reached the maximum,the hardness of the consolidated layer was the highest,and the development of the pore and throat network was optimum at a depth of 10–15 mm.

The Application of Impact Echo Scanning on Nondestructive Test of Pavement

A new nondestructive test method-Impact Echo Scanning was introduced. Application of this method on pavement structure test was discussed. A method to increase the measurement accuracy of the test on multi-layers was proposed, and was verified by field test. The test results show that the basic structural information can obtained rapidly and accurately by 3-D scanning of the impact echo system.

Research on wind erosion processes and controlling factors based on wind tunnel test and 3D laser scanning technology

The study of wind erosion processes is of great importance to the prevention and control of soil wind erosion.In this study,three structurally intact soil samples were collected from the steppe of Inner Mongolia Autonomous Region,China and placed in a wind tunnel where they were subjected to six different wind speeds(10,15,17,20,25,and 30 m/s)to simulate wind erosion in the wind tunnel.After each test,the soil surfaces were scanned by a 3D laser scanner to create a high-resolution Digital Elevation Model(DEM),and the changes in wind erosion mass and microtopography were quantified.Based on this,we performed further analysis of wind erosion-controlling factors.The study results showed that the average measurement error between the 3D laser scanning method and weighing method was 6.23%for the three undisturbed soil samples.With increasing wind speed,the microtopography on the undisturbed soil surface first became smooth,and then fine stripes and pits gradually developed.In the initial stage of wind erosion processes,the ability of the soil to resist wind erosion was mainly affected by the soil hardness.In the late stage of wind erosion processes,the degree of soil erosion was mainly affected by soil organic matter and CaCO_(3)content.The results of this study are expected to provide a theoretical basis for soil wind erosion control and promote the application of 3D laser scanners in wind erosion monitoring.

A Portable Noncontact Profile Scanning System for Aircraft Assembly

Three-dimensional(3D)profile scanning plays a crucial role in the inspection of assembled large aircraft.In this paper,to achieve noncontact automatic measurements of the high-reflective profiles of large-scale curved parts and components,an automated noncontact system and method with high accuracy and high efficiency are presented.First,a hybrid 3D coordinate measurement system based on proximity sensors and cameras is proposed to obtain noncontact measurements while avoiding the influence of high reflection on the measurement accuracy.A hybrid measurement model that combines the one-dimensional distances measured by the proximity sensors and the 3D information obtained by cameras is proposed to determine high-accuracy 3D coordinates of the measured points.Then,a profile-driven 3D automated scanning method and strategy are designed to rapidly scan and reconstruct the profile within the effective range without scratching the profile or exceeding the measurement range of the proposed system.Finally,experiments and accuracy analyses are performed in situ on an assembled tailplane panel(approximately 1760 mm×460 mm).The automated scanning process is completed in a timeframe of 208s with an average error of less than 0.121 mm for profile reconstruction.Therefore,the proposed method is promising considering both the high accuracy and high efficiency requirements of profile inspections for large aircraft.

Prediction of carbonate permeability from multiresolution CT scans and deep learning

The low-resolution CT scan images obtained from drill core generally struggle with problems such as insufficient pore structure information and incomplete image details.Consequently,predicting the permeability of heterogeneous reservoir cores relies heavily on high-resolution CT scanning images.However,this approach requires a considerable amount of data and is associated with high costs.To solve this problem,a method for predicting core permeability based on deep learning using CT scan images with diff erent resolutions is proposed in this work.First,the high-resolution CT scans are preprocessed and then cubic subsets are extracted.The permeability of each subset is estimated using the Lattice Boltzmann Method(LBM)and forms the training set for the convolutional neural network(CNN)model.Subsequently,the highresolution images are downsampled to obtain the low-resolution grayscale images.In the comparative analysis of the porosities of diff erent low-resolution images,the low-resolution image with a resolution of 10%of the original image is considered as the test set in this paper.It is found that the permeabilities predicted from the low-resolution images are in good agreement with the values calculated by the LBM.In addition,the test data are compared with the results of the Kozeny-Carman(KC)model and the measured permeability of the whole sample.The results show that the prediction of the permeability of tight carbonate rock based on deep learning using CT scans with diff erent resolutions is reliable.

Quantitative investigation of multi-fracture morphology during TPDF through true tri-axial fracturing experiments and CT scanning

Due to the reservoir heterogeneity and the stress shadow effect, multiple hydraulic fractures within one fracturing segment cannot be initiated simultaneously and propagate evenly, which will cause a low effectiveness of reservoir stimulation. Temporary plugging and diverting fracturing(TPDF) is considered to be a potential uniform-stimulation method for creating multiple fractures simultaneously in the oilfield. However, the multi-fracture propagation morphology during TPDF is not clear now. The purpose of this study is to quantitatively investigate the multi-fracture propagation morphology during TPDF through true tri-axial fracturing experiments and CT scanning. Critical parameters such as fracture spacing, number of perforation clusters, the viscosity of fracturing fluid, and the in-situ stress have been investigated. The fracture geometry before and after diversion have been quantitively analyzed based on the two-dimensional CT slices and three-dimensional reconstruction method. The main conclusions are as follows:(1) When injecting the high viscosity fluid or perforating at the location with low in-situ stress, multiple hydraulic fractures would simultaneously propagate. Otherwise, only one hydraulic fracture was created during the initial fracturing stage(IFS) for most tests.(2) The perforation cluster effectiveness(PCE) has increased from 26.62% during the IFS to 88.86% after using diverters.(3) The diverted fracture volume has no apparent correlation with the pressure peak and peak frequency during the diversion fracturing stage(DFS) but is positively correlated with water-work.(4) Four types of plugging behavior in shale could be controlled by adjusting the diverter recipe and diverter injection time, and the plugging behavior includes plugging the natural fracture in the wellbore, plugging the previous hydraulic fractures, plugging the fracture tip and plugging the bedding.

Cryostructures and ground ice content in ice-rich permafrost area of the Qinghai-Tibet Plateau with Computed Tomography Scanning

Permafrost is an important part of the cryosphere,playing an integral role in the hydrologic cycle,ecology,and influencing human activity.Melting of ground ice can drastically change landscapes and associated thaw subsidence may induce instability of infrastructure.The terrain conditions on the Qinghai-Tibet Plateau are complex,and the spatial distribution of ground ice is highly variable,so knowledge of its abundance and variability is required for impact assessments relating to the degradation of permafrost.This study examined 55 permafrost samples from warm,ice-rich permafrost region in Beiluhe Basin,Qinghai-Tibet Plateau.The samples were examined using Computed Tomography scanning,and the ice content and cryostructure were determined.The results indicated that:1)variation in volumetric ice content was considerable(0%-70%),with a mean value of 17%;2)seven cryostructures were identified,including crustal,vein,lenticular,ataxitic,reticulate and layered cryostructure;3)volumetric ice content varied by cryostructure,with the highest associated with layered and ataxitic cryostructures.Volumetric ice contents were lowest for samples with pore and lenticular cryostructures.This work provides detailed ground ice content and will be helpful for assessing thaw subsidence and infrastructure stability on Qinghai-Tibet Plateau.

^(131)I-SPECT/CT断层显像指导DTC分期及诊疗的价值

目的探讨^(131)I-SPECT/CT断层显像指导分化型甲状腺癌(DTC)分期及诊疗的价值。方法选取我院2021年3月-2024年3月收治的210例首次接受^(131)I治疗患者为研究对象,于治疗后48~72 h完成^(131)I-SPECT/CT断层显像及^(131)I全身显像(WBS),分析^(131)I-SPECT/CT断层显像在DTC分期和诊疗中的应用价值。结果210例患者DTC经过^(131)I-W BS检查发现252个异常摄碘灶,其中甲状腺残留68个病灶(26.98%)、颈部淋巴结转移109个病灶(43.25%)、可疑病灶23个病灶(9.13%)、远处转移52个病灶(20.63%);经过^(131)I-SPECT/CT检查确定甲状腺残留49个病灶(19.44%)、颈部淋巴结转移135个病灶(53.57%)、颈部污染8个病灶(3.17%)、远处转移60个病灶(23.81%)。252个病灶经过半年以上的^(131)I-SPECT/CT、超声、CT结果随访及临床医生意见等综合判断,发现有197个转移灶,55个单纯残留病灶;^(131)I-WBS诊断184个转移灶,68个单纯残留病灶;^(131)I-SPECT/CT诊断195个转移灶,57个单纯残留病灶。^(131)I-SPECT/CT断层显像灵敏度、特异度、准确度、阳性预测值、阴性预测值高于^(131)I-WBS(P<0.05);且~(31)I-SPECT/CT断层显像诊断DTC转移灶与金标准一致性高于^(131)I-WBS(Kappa值分别为0.931、0.668)。根据^(131)I-SPECT/CT断层显像结果,210例DTC患者中有34例临床分期从M1期调整为M2期,有8例临床分期从M2期调整为M3期,共改变42例患者的术后分期。且基于临床分期及^(131)I-SPECT/CT断层显像结果我科共调整42例(20.00%)DTC患者^(131)I治疗方案。结论^(131)I-SPECT/CT断层显像可指导DTC患者术后分期,弥补^(131)I-WBS的不足,为DTC患者1311治疗方案制定提供可靠依据。

Hemangioblastoma Incidentally Discovered at CT Scan in Bamako: About a Case

Hemangioblastomas are benign vascular tumors of the brain. These are rare tumors, usually located in the cerebellum and most often affecting young adults. The aim was to study the value of CT in the management of hemangioblastoma through observation. We report the case of a 38-year-old patient referred to the radiology and Medical Imaging Department of the Marie Curie Medical Clinic in Bamako, Mali, for an orbito-cerebral CT scan in a context of bilateral eyelid edema. The examination was performed using multi-slice computed tomography (16 slices) with reconstruction in the 3 planes of space without and with the injection of an iodinated contrast agent. The CT scan was crucial in making the diagnosis of hemangioblastoma incidentally, which allowed for adequate management. The patient was operated on, and the radiological outcome was favorable, without significant cystic formation, after postoperative control and clinical signs were resolved. CT can be an interesting alternative in countries like ours despite MRI being the examination of choice in hemangioblastomas.

肺栓塞诊断中多层螺旋CT双期动态增强扫描技术的应用研究

目的 分析研究肺栓塞诊断中应用多层螺旋CT双期动态增强扫描技术的应用价值。方法 选取河南省胸科医院2020年2月至2022年6月收治的50例疑似肺栓塞患者,选择SOMATOM Definition Flash双源CT扫描机开展胸部平扫和肺动脉期、肺静脉期双期动态增强CT扫描,分析双期动态增强扫描图像;以综合评定结果为金标准,计算双期动态增强CT扫描检查结果。结果 分析多层螺旋CT双期动态增强扫描图像发现,41例患者诊断为肺栓塞,能精确发现145处栓子,其中13处为左右肺动脉主干,57处为叶动脉,55处为段动脉,18处为亚段动脉,2处为亚亚段动脉。50例患者经综合评估,结果为阳性48例,阴性2例,双期动态增强CT扫描检查结果为阳性46例,阴性4例。双期动态增强CT扫描检查敏感度为95.83%(46/48),特异度为100.00(2/2),准确度为96.00%(48/50)。结论 临床诊断肺栓塞时采用多层螺旋CT双期动态增强扫描技术具有显著的检测和诊断效果,准确性、特异性及敏感度均较高,值得应用。

Study of Scanning Dose Optimization on Chest and Abdomen Enhanced CT Imaging

Objective: To investigate the correlation between radiation dose and radiation risk when patients are scanned by 64-slice spiral CT. Materials and Methods: SPSS 17.0 is used statistically for analyzing the patient’s scanning parameters, radiation dose of monitoring and examining the patients who are scanning of their abdomen, chest and pelvic in our affiliated hospital. Results: SPSS statistical analysis shows that the factor related to radiation dose is scanning layer;the basic characteristics such as height and heart rate don’t affect the patient’s scan dose directly. Conclusion: Increasing the delay time after injection can reduce the scan numbers and monitoring layers of the machine, thus reduce the patient’s radiation dose and tube’s exposure time.

Application of Dual-Source CT TurboFlash Coarse Pitch Scanning in Coronary Artery Imaging

Objective: To compare and analyze the image quality and radiation dose of three scanning modes of dual-source CT coronary artery retrospectively, and to discuss the application value of TurboFlash coarse pitch scanning mode. Methods: The imaging data of 100 patients who underwent CT coronary angiography (CCTA) using Siemens force CT retrospective gated triggering spiral scan (RES-SPIRAL), adaptive prospective gated triggering sequence scan (SEQ) and prospective coarse pitch scan (TurboFlash) retrospectively was collected. The image quality was evaluated by objective and subjective methods. The effective radiation dose of patients was compared and analyzed, and the indications of the three scanning modes were analyzed. The application value of dual-source CT TurboFlash coarse pitch scanning in coronary artery imaging was evaluated. Results: The results showed that the left main coronary artery, the right coronary artery and their tertiary branches could be clearly displayed in the three groups of images: the left anterior descending branch, the left circumflex branch, and their three-level branches. There was no statistical difference in subjective image quality among the three groups of pictures (P > 0.05). There was no statistical difference in objective evaluation indexes, such as CT value, SNR, CNR and Noise among the three groups (P > 0.05). The patient radiation dose results showed that the effective radiation dose ED of RES-SPIRA scan was (9.22 ± 1.33) mSv. The dose of SEQ was (2.88 ± 2.47) mSv, and the dose of TurboFlash was (0.51 ± 0.16) mSv. There was significant difference in comparison of the three groups (P 0.05). RES-spiral scanning had the highest radiation dose and TurboFlash coarse pitch scanning (TurboFlash) had the lowest radiation dose. Conclusion: TurboFlash coarse pitch scanning is low in dosage, fast in speed and wide in adaptability. It is especially suitable for the elderly, children, coma and other patients who cannot cooperate with breath-holding examination, as well as for the screening and examination of coronary artery diseases in asymptomatic population. Undoubtedly, it is a worthy method of heart coronary artery examination.

Correlation between CT dynamic enhanced scanning parameters and serum tumor markers before and after radiofrequency ablation in patients with lung cancer

Objective:To study the correlation between CT dynamic enhanced scanning parameters and serum tumor markers before and after radiofrequency ablation in patients with lung cancer.Methods:60 patients with advanced non-small cell lung cancer who were treated in this hospital between January 2015 and January 2017 were divided into control group(n=30)and observation group(n=30)by random number table method.Control group received conventional intravenous chemotherapy,and observation group received intravenous chemotherapy combined with radiofrequency ablation.The differences in CT dynamic enhanced scanning parameter levels and serum tumor marker contents were compared between the two groups of patients before and after treatment.Pearson test was used to evaluate the correlation between CT dynamic enhanced scanning parameters and serum tumor marker contents in patients with advanced non-small cell lung cancer.Results:Before treatment,the differences in CT dynamic enhanced scanning parameter levels,non-organ-specific tumor marker contents and vascular tumor marker contents were not statistically significant between the two groups of patients(P>0.05).After treatment,CT dynamic enhanced scanning parameters PH and perfusion value levels of observation group were lower than those of control group(P<0.05);serum non-organ specific tumor markers CA125,CA153,CEA and CYFRA21-1 contents of observation group were lower than those of control group;serum vascular tumor markers VEGF,Ang-2,HIF-1 and MMP-9 contents were lower than those of control group(P<0.05).Pearson test showed that CT dynamic enhanced scanning parameters PH and perfusion value levels in patients with non-small cell lung cancer were positively correlated with serum non-organ specific tumor marker and vascular tumor marker contents.Conclusion:Adjuvant radiofrequency ablation can significantly reduce the tumor malignancy of patients with advanced non-small cell lung cancer.

Test Accuracy of CT-Scan for the Detection of Malignant Liver Mass

Background: Detection of malignant liver mass is very important for the treatment modalities. Objective: The purpose of the present study was to establish the usefulness of CT scan in the diagnosis of malignant hepatic mass. Methodology: This cross sectional study was carried out in the Department of Radiology and Imaging at Mymensingh Medical College Hospital (MMCH), Mymensingh, Banghabandhu Sheikh Mujib Medical University (BSMMU), Dhaka and Dhaka Medical College Hospital (DMCH), Dhaka during the period of 1st January 2006 to 31st December 2007. Patients admitted in the Department of Medicine and Department of Hepatobiliary of MMCH, BSMMU, and DMCH with the clinical diagnosis of fever, abdominal pain, anorexia, nausea/vomiting, loss of appetite, jaundice, weight loss and ascites were selected as study population. CT scan and histopathology were performed to all the patients. Result: A total number of 50 patients were recruited for this study. Mean age of all patients was 51.28 ± 14 years with a range of 17 year to 78 years. Among all patients 28 had multiple lesion, of them 71.4% was malignant and 28.6% was benign. On the other side 22 patients had solitary lesion, of them 36.4% was malignant and 63.6% was benign

CT学习模型预测重型颅脑操作预后的临床研究

目的 评估一个结合头部CT扫描和临床信息的深度学习预后模型,以预测重型颅脑损伤(severe traumatic brain injury,STBI)预后的长期结果。方法回顾性分析本院2020年1月至2023年4月收治的537名STBI患者的临床资料,应用头部CT卷积神经网络预测6个月后死亡率和不良结局,形成整体融合模型等。并纳入同期的220名STBI患者对模型进行评估,将融合模型与国际预后和临床试验分析TBI模型(IMPACT)和三位专科医生的预测进行比较,AUC曲线下面积被用作主要模型性能指标。结果在内部数据集上,融合模型在预测死亡率(AUC,0.92[95%CI:0.86,0.97]vs 0.80[95%CI:0.71,0.88];P=0.001)和不良结局(AUC,0.88[95%CI:0.82,0.94]vs 0.82[95%CI:0.75,0.90];P=0.04)方面比IM PACT模型有更高的AUC。在创伤性脑损伤试验中,与IMPACT模型(AUC,0.83;95%CI:0.77,0.90)相比,没有证据表明任何模型在预测死亡率方面存在显著差异。影像模型(AUC,0.73;95%CI:0.66-0.81;P=0.02)和融合模型(AUC,0.68;95%CI:0.60,0.76;P=0.02)在预测不良结局方面不如IMPACT模型(AUC,0.83;95%CI:0.77,0.89)。融合模型的表现超过了专科医生的预测。结论头部CT和临床信息的深度学习模型可以用来预测重型颅脑损伤后6个月的预后。

基于CT技术的黄原胶加固土干湿循环条件下力学性能和微观结构劣化机制研究

干湿循环对岩土体的工程特性具有重要影响。采用CT扫描技术和力学测试,对加入不同含量黄原胶(0%,0.5%,1.5%)加固的黏土在经历不同次数(0,1,4,8,12次)干湿循环作用下的力学性能和微观结构劣化机制进行了研究,得到结论:(1)黄原胶能够有效提高土体的抗压强度和耐干湿循环效果。随着黄原胶含量的增加,干湿循环作用后的强度损失逐渐减小,当循环次数从0次增加到4次时,对于加入黄原胶含量分别为0%,0.5%,1.5%的试样,抗压强度分别损失了42.75%,17.2%,14.04%。(2)加固土的抗压强度与干湿循环次数之间保持指数下降的关系,当循环次数达到4次后,随着循环次数的进一步增加,抗压强度和弹性模量均在较小的变化范围内波动。(3)随着干湿循环次数的增加,黄原胶加固土的孔隙率表现出先增加后减小的趋势,连通孔隙不断扩展,而孤立孔隙表现出先增加后减小的趋势。(4)随着试样的干燥,黄原胶在土颗粒间形成网状基质,提高土体的强度和耐干湿循环能力。

基于Test Director6和边界扫描的板级测试技术

在国内首次介绍了Qmax公司的Test Director6开发工具在JTAG测试中的应用,并首次提出了利用Test Director6进行基于JTAG技术的板级测试方法。实验证明,该方法成熟高效,能有效提高测试效率和测试可靠性,具有较大的实用价值。